Battery temperature sensor installation and compatibility

We are installing the solar system in the next house here out in the middle of nowhere. There is an option for a remote battery temperature sensor on the charge controller. The stuff that I can get locally is a Morningstar TriStar TS45 PWM controller and a Magnum Energy remote temperature sensor. Are these compatible? According to what I have been able to read you just bolt the temperature sensor to a battery post?!? It seems to me you'd want the temperature sensor to be a little more "intimate" with the battery, perhaps by setting the battery on top of the sensor or somehow fastening it to the battery case. I know you cannot put it in the cell but putting it on the terminal seems like it is kind of just hanging out in the breeze and not really sensing the battery temperature.

If these two components are compatible does anyone have a wiring diagram? Is a wiring diagram even needed?

Comments

Actually, the post is a pretty good spot. There is a big chunk of metal that goes into the battery, and it creates a better thermal path than trying to glue it to the side of a plastic case.

As to what the value of the thermistor inside it is, I've got no idea. If it was known that a $1 thermistor would work, the vendors would not sell many $12 ones with 8' of wire already attached . (must be good wire for $10 and a crimp lug to hold the thermistor.)

On a Morningstar TS-60 (PWM) CC, the sensor has about 15 Kohm resistance at about 20 degrees C -- NTC.

Battery Flag Terminals are well connected to the plates of most batteries, so a sensor on the flag terminal is not just hanging in the breeze. Personally, I mount BTS/RTSes midway down on the case of a battery in the center of the pack. Then hog out an area in 1-inch thick white Styrofoam insulation that will allow the sensors to have room, but still be insulated. Then the styro is taped or strapped to that battery. Place all of the sensors (from each charge source) on that same battery, all under the insulation. This helps keep ambient temp variations from affecting the sensors.

Sorry, too bad that there is not a FAQ for resistance values for BTSes supplied by all common manufacturers. The Morningstar RTS uses pigtails to screw terminals. Most others I've seen use phone plug RJ-11 (?) in the USA. Good Luck, Vic

that would be true and it would be important no matter what to have good connections and to check them now and again. even if somebody would use undersized wires that heat can build on the wires and could also transfer to the battery connections and posts. hopefully, one would not undersize their wires either as that and bad connections could be dangerous and not just fool a bts.

No, they are NOT compatible - or if they are, it would be totally by accident. There are hundreds of different types of temperature sensing devices, and almost all mfg's use a different one. For an idea of how many types there are, see http://www.omega.com/temperature/z/zsection.asp

Sometimes you can tell by the lead colors, but not always http://www.omega.com/temperature/Z/pdf/z256-257.pdf. BTW, the Omega website has a wealth of info on various types of temperature products and dozens of tech papers if you really want to get into it.

I was concerned that the Magnum sensor would not be compatible with the MorningStar controller.

I know with thermocouples there are only a few types but perhaps with what I'll assume is a thermistor there are more variations and of course a manufacturer could always put an extra resistor in somewhere to mess up everything.

Speaking of battery temperature - - slightly off topic - - didn't bother insulating my bank last year and their temp never went below +1 or +2C. This morning the TriStar is telling me they're at -7C. Guess I should have insulated them after all. On the other hand, perhaps our cold winters is part of the reason they've last 10 years in spite of my abusing them in their early life?

OK, so the battery temperature sensor is very likely incompatible with the controller. Is a battery temperature sensor important or a good thing to have? This installation is inside the house and the controller and batteries are both in the same room and within a few feet of each other.

The controller is a Morningstar Tristar TS45 and the batteries will be a pair of Deka 225Ah Solar Gel batteries. If a temperature sensor is a good idea I might be able to get the right one sent out as I cannot get one in country.

Is a battery temperature sensor important or a good thing to have? This installation is inside the house and the controller and batteries are both in the same room and within a few feet of each other.

If the batteries are always at standard temperature you do not need a temp sensor. Remember though, that batteries heat up when they are charged or discharged, more heating with larger currents.

If the batteries are not at standard temperature, but are at a fairly constant temperature you can just manually compensate for temperature by adjusting your absorb, float, and equalize voltages. Of course, you have equalize function turned off because you have gel cell batteries.
--vtMaps

gels are very picky and you must be careful in charging them.
i don't know if these are the batteries you have, but if not then look up the charging parameters for yours elsewhere on their site,http://www.dekabatteries.com/assets/base/0919.pdf
note the .003v/degree c specification and be sure the controller you have can be changed to suit.

I've got the Morningstar battery temperature sensor and I just checked the ohms across the Morningstar and Magnum and it is significantly different when both are at ambient (+80 degrees). I'll stick with the Morningstar to match the controller.

Now another question. Any problem with cutting the wire a little shorter? I don't need 10m of cable. I've got to assume a shorter cable is better or is the cable length somehow factored into the resistance of the thermistor?

vtmaps, there are two systems. My house with lead acid batteries in an outside store room and the next house with small kids and the gel batteries in an inside storeroom. The temp sensor is for the gel batteries.

Don't see a reason not to shorten the wire as long as both legs are kept the same length. The one case I can think of is the leg wire resistance is included in the temperature measuring algorithm but normally that shouldn't be the case.

Just to add some info for anyone who finds this thread when searching for temp sensor info.

Based on playing with a potentiometer hooked to 2 different Morningstar controllers (Prostar PWM gen2 and gen3) and watching how their resistance affected the reported temperature, they use an NTC thermistor with specs of 10 kohm @25C, a beta of ~3900 and alpha of around -4.4. US Sensor PT103J2 or AC103J2F, or Amethem ACC-104 would work well (available from Mouser for a couple of bucks each). If you're cheap, a Vishay NTCLE203E3103SB0 is in the ballpark for less than a buck.